Iranian pilgrims will not be allowed to participate in the annual Muslim Hajj pilgrimage to Mecca this year, Iranian authorities announced on Sunday, accusing Saudi Arabia of making insufficient safety arrangements for Iranian citizens. The decision escalates tensions between Iran and Saudi Arabia, playing out throughout the region, but also rests upon questions of whether Saudi Arabia has done enough to guarantee pilgrims' safety after last September's disaster, when hundreds and perhaps thousands of worshippers were killed in a stampede.

More than 2 million Muslims participated in last year's Hajj. The annual pilgrimage is one of the Five Pillars of Islam, which requires that all Muslims able to make the trip do so at least once in their lifetime. This year's Hajj will take place in September.

Saudis have refused to give Iranian pilgrims consular support, Iranian Foreign Ministry spokesman Hossein Jaberi Ansari told Iran's Channel 3, according to CNN. The Iranian Hajj Organization said it had worked with the Iranian government to allow pilgrims to honor the custom, but talks with Saudi Arabia did not go far enough.

"Our efforts have remained unheard by Saudis, since they would not issue visa for Iranians somewhere inside Iran, thus rendering it impossible to use Iran Air flights to transfer the passengers," the group said a statement.

Saudi officials, however, contend Iran had ulterior motives for barring its pilgrims from the Hajj. "The Iranian Hajj Organization's refusal to sign the minutes of the Hajj arrangements shows an intent of distorting the rite of Hajj and politicizing it before its own people and the world," said Sheikh Dr. Saleh bin Abdulrahman bin Sulaiman Mohaimeed, the head of the Public Court in the Medina region, as CNN reported.

Safety issues have troubled the pilgrimage, one of the largest annual gatherings on Earth, for years. A stampede during last September was the most deadly. The Associated Press estimates that more than 2,400 worshippers lost their lives. More than 450 were from Iran, according to the Iranian authorities, who have accused Saudis of underreporting the deaths. Saudi Arabia claims about 700 people were killed, while Iran says more than 4,500 died, according to The New York Times.

Saudi Crown Prince Mohammed bin Nayef, who is in charge of Hajj security, announced in May that the Interior Ministry is taking steps to make sure a repeat of last year's disaster does not occur, such as establishing a more sophisticated operations control room to monitor the Mecca. Around 1,600 security personnel will be monitoring 1,800 closed-circuit TV cameras every hour of the day.

The advanced security should allow the ministry to respond quickly if a crisis develops in order to circumvent another disaster. Trained personnel around the grounds who speak various languages, including English, will also be able to help control the crowd and give special attention to handicapped pilgrims. The crown prince did not, however, make any reference to last year's tragedy when he announced the initiatives.

The Iranian pilgrim ban comes amid ongoing tensions between Iran and Saudi Arabia, worsened by the conflict in Syria, where the two countries back opposite sides: Iran supports President Bashar al-Assad, while Saudis have supported rebel groups. Diplomatic ties were cut off this year after Iranians stormed the Saudi embassy in Tehran, protesting the execution of a Shia cleric in Saudi Arabia. Iran has also banned Saudi imports.

The Hajj ban is set to take a further economic toll on Saudi Arabia, which brings in about $18 billion every year from religious tourism, CNN reports: Iranians are typically one of the best-represented countries at the Hajj.

But the costs may be be worth Saudi Arabia's goal of isolating Iran, as Bruce Riedel, the director of The Brookings Institution's Intelligence Project, wrote in a column for Al-Monitor.

"Saudi Arabia is escalating its campaign to delegitimize Iran and limit its influence in the Islamic world," Mr. Riedel writes, noting that "most Islamic states will not sever ties to Tehran, but if a number do follow the Saudis' lead, Iran will lose face. Rather than ending its status as a pariah state following the nuclear deal with Western powers, Iran will still be out of the Muslim mainstream."